1. Field of the Invention
The present invention relates to a scanning apparatus for providing a plurality of scanning beams.
2. Description of the Prior Art
In an attempt to obtain plural scanning beams with the use of a single scanner, the possibilities are, to split a single scanning beam coming from the scanner into plural scanning beams, and to direct plural stationary beams to a scanner in different directions. The present invention is concerned with the latter method.
If, in such a case as the present invention is concerned, plural beams impinge upon the deflecting surface of the scanner in different directions without superposition therebetween, the centers of deflection of the scanning beams are different from each other. There is a difficulty in optically processing such scanning beams, for example, imaging these scanning beams on a surface to be scanned, by means of a single scanning lens. Generally speaking, in an optical system for handling a scanning beam, the center of deflection and the entrance pupil of the optical system coincide. If the scanning beams having different centers of deflection are handled by the optical system, it means that the entrance pupil becomes larger, that is, the F-number becomes smaller, thus making the designing of the optical system more difficult.